A low molecular weight extract of bovine serum albumin stimulates rabbit blastocyst cell division and expansion in vitro.

Fraction V bovine serum albumin (BSA) was dissolved in 5% formic acid and filtered through a molecular filter with a cutoff of Mr 10 000. The freeze-dried filtrate stimulated increased cell division of cultured rabbit morulae to blastocysts (up to 8-fold increase in cell number) and increased blastocyst expansion (greater than 2-fold). These results show that some samples of commercial BSA contain an embryonic growth factor of a low molecular weight.